Chapter 1

Front 1

threat

Back 1

any condition that compromises the validity related to a research design.

Front 2

internal validity

Back 2

the extent to which the outcome was based on the independent variable (i.e., the treatment), as opposed to extraneous or unaccounted for variables.

Front 3

external validity

Back 3

the extent to which the results can be generalized to the relevant populations, settings, treatments, or outcomes; can be secured if a true probability sampling technique (e.g., random selection) is utilized, although, logistically this is often extremely difficult.

Front 4

History (threat to internal validity)

Back 4

any event that occurs during the time of the treatment and the posttest that could affect the outcome (e.g., natural life events such as death in the family, change in job, or moving).

Front 5

maturation (threat to internal validity)

Back 5

the natural process of changing, growing, and learning over time.

Front 6

testing (threat to internal validity)

Back 6

the effects of practice familiarity in taking the same test more than once (e.g., the participant who takes the same math achievement test twice in the pretest and posttest measures may improve performance simply because of the familiarity with the test).

Front 7

instrumentation (threat to internal validity)

Back 7

the change in a measuring instrument over time (i.e., some instruments undergo revisions).

Front 8

statistical regression (threat to internal validity)

Back 8

the tendency for any extreme score to regress toward the average (i.e., regression toward the mean is a statistical phenomenon that any extreme scores, high or low, eventually regress or revert back to the average.

Front 9

selection bias (threat to internal validity)

Back 9

Also known as selection effect, this results when researchers do not use a systematic assignment technique (e.g., random assignment) to assign participants to conditions.

Front 10

attrition (threat to internal validity)

Back 10

the loss of participants during the term of the experiment.

Front 11

combination of selection and other treatments (threat to internal validity)

Back 11

any one of the threats to internal validity can affect one of the groups in the study as opposed to the other (e.g., the participants in one condition may have been exposed to a stressful event not related to the experiment, but this event does not affect the other condition).

Front 12

diffusion (threat to internal validity)

Back 12

the inadvertent application of the treatment to the control group (e.g., in educational settings, teachers may utilize aspects of the math intervention in the control group that are supposed to be delivered only to the control condition.

Front 13

special treatment (threat to internal validity)

Back 13

the control group may receive special attention, and the changes may be attributed only to the attention (i.e., the placebo effect)

Front 14

sequencing effects (threat to internal validity)

Back 14

sequencing is an issue related to within-subject (repeated measures) approaches; also known as multiple-treatment interference, fatigue effects, and practice effects. Sequencing can be separated into order effects (i.e., the order in which participants receive the treatment can affect the results) and carryover effects (i.e., performance in one condition affects performance in another condition)

Front 15

sample characteristics (threat to external validity)

Back 15

the extent to which the sample (i.e., unit) represents the population from which it is drawn (i.e., for a sample to represent a population, the researcher must employ the appropriate sampling procedures and perform random selection).

Front 16

stimulus characteristics and settings (threat to external validity)

Back 16

the unique factors involved in providing the treatment or intervention, such as the setting and researchers (i.e., it is difficult to replicate contrived laboratory conditions to real-life scenarios)

Front 17

treatment variations (threat to external validity)

Back 17

variations in the same treatment or the combination of multiple or partial treatments account for different results.

Front 18

outcome variations (threat to external validity)

Back 18

observing the effect of one type of outcome differs when alternate outcomes are observed.

Front 19

context-dependent mediation (threat to external validity)

Back 19

mediating variables related to outcomes differ between contexts or settings.